3D part control using multiple pass liquid delivery

Abstract

According to an example, a 3D printer may include a delivery device and a controller. The controller may access a morphology of a part to be formed from a plurality of build materials in a layer, determine, based upon the accessed morphology, a first delivery pattern for the delivery device to selectively deliver liquid droplets onto build materials in the layer during a first pass over the layer and a second delivery pattern for the delivery device to selectively deliver liquid droplets onto build materials in the layer during a second pass over the layer to control a property of the part formed of some of the build materials in the layer. The controller may also control the delivery device to selectively deliver liquid droplets onto build materials in the layer according to the determined first and second delivery patterns respectively during the first pass and the second pass.

What is claimed is: 
     
       1. A three-dimensional (3D) printer comprising:
 a first delivery device to selectively deliver first liquid droplets onto a first layer of build materials as the first delivery device is scanned across the first layer; and 
 a controller to:
 access a morphology of a part to be formed from the first layer of the build materials, wherein the morphology of the part comprises expected temperatures across the first layer of the build materials; 
 determine a certain amount of the first liquid droplets to be delivered onto the first layer of the build materials to form a portion of the part in the first layer of the build materials; 
 split the certain amount of the first liquid droplets into a first amount to be delivered during a first pass of the first delivery device and a second amount to be delivered during a second pass of the first delivery device, wherein the first amount and the second amount are determined based on the expected temperatures across the first layer of the build materials; and 
 control the first delivery device to selectively deliver the first amount of the first liquid droplets onto the first layer of the build materials according to a first delivery pattern during the first pass and the second amount of the first liquid droplets onto the first layer of the build materials according to a second delivery pattern during the second pass. 
 
 
     
     
       2. The 3D printer according to  claim 1 , further comprising:
 a fusing radiation generator to apply fusing radiation onto the first layer of build materials as part of a layer processing operation, and wherein the second pass of the first delivery device occurs at least one of prior to and following the fusing radiation generator applying fusing radiation onto the first layer during the layer processing operation after the first pass. 
 
     
     
       3. The 3D printer according to  claim 1 , wherein the morphology of the part further comprises distances between boundaries of the part and other parts to be formed of other build materials in the first layer. 
     
     
       4. The 3D printer according to  claim 1 , further comprising:
 a second delivery device to selectively deliver second liquid droplets onto the build materials in the first layer as the second delivery device is scanned across the first layer; and 
 wherein the controller is further to:
 determine, based upon the expected temperatures across the first layer of the build materials, a third delivery pattern for the second delivery device to selectively deliver the second liquid droplets onto the first layer of the build materials during a third pass; and 
 control the second delivery device to selectively deliver the second liquid droplets onto the first layer of the build materials in the first layer according to the determined third delivery pattern during the third pass. 
 
 
     
     
       5. The 3D printer according to  claim 4 , wherein the controller is further to determine, based upon the expected temperatures across the first layer of the build materials, a fourth delivery pattern for the second delivery device to selectively deliver the second liquid droplets onto the first layer of the build materials a fourth pass and to control the second delivery device to selectively deliver the second liquid droplets onto the first layer of the build materials according to the determined fourth delivery pattern during the fourth pass. 
     
     
       6. The 3D printer according to  claim 4 , wherein the first liquid droplets and the second liquid droplets have different radiation absorption properties with respect to each other. 
     
     
       7. The 3D printer according to  claim 1 , wherein the controller is further to access sensed temperature information of the build materials in the first layer and to implement the sensed temperature information to determine the first delivery pattern and the second delivery pattern. 
     
     
       8. The 3D printer according to  claim 1 , wherein the controller is to split the certain amount of the first liquid droplets into the first amount to be delivered during the first pass and the second amount to be delivered during the second pass to control a property of the part to be formed, wherein the property of the part to be formed comprises a mechanical property of the part, a color property of the part, a finishing property of the part, or a combination thereof.